The formation and use of streams of liquid propelled by very high pressure to very high speeds is well known in the industry. Such streams are used for cleaning surfaces of dirt and contaminants and for removing coatings such as paint. Some researchers have noted that non-steady streams are more effective than steady streams for these applications. In non-steady applications, the stream is broken up into slugs or drops. See, for example, U.S. Pat. No. 3,983,740 incorporated herein by reference.
The prior art in this area of technology has suffered from several drawbacks including, but not limited to, the need to use a complex driver, such as a high frequency ultrasonic generator, or the like, for causing formation of the slugs or drops. Further, without a driver, other prior art devices are unsuitable for commercial exploitation due to the fact that the distance required for a stream of liquid to break up into drops is too long to provide a commercially usable device.